Continuous processing of filamentary tow



1953 I I H. B. MERRIMAN I 2,657,433

CONTINUOUS PROCESSING OF FILAMENTARY TOW Filed Oct. 29, 1951 //7 van 10Horace Barf/effMemman By his af/omeys NUMW M M Patented Nov. 3, 1953CONTINUOUS PROCESSING OF FILAMENTARY TOW Horace B. Merriman, Coventry,England, assignor to Courtaulds Limited, London, England, a

British company Application October 29, 1951, Serial No. 253,706 Claimspriority, application in Great Britain November 14, 1950 This inventionrelates to the continuous processing of filamentary tow and moreparticularly to spreading a compact tow of substantially parallelcontinuous filaments into a flat band of substantially uniformthickness.

In the production of a tow of continuous rayon filaments, for exampleviscose rayon filaments, filaments from a number of multi-hole jets areusually led together to form a thick tow havin a denier which is atleast 50,000 and which may be as high as 1,000,000. The resultant tow issubjected to a number of wet treatments such as desulphurising, washingand bleaching, followed by drying, for example on a series of heatedrollers. Before the drying stage, the tow is usually mangled by passagethrough the nip of a pair of squeeze rollers to remove surplus treatmentliquid. The tow passing from the squeeze rollers is therefore generallyin the form of a compact mass which is difficult to dry uniformly andquickly on the heated drying rollers because the tow has a small ratioof surface area to unit volume and th heat does not readily reach thecentral filaments.

The object of the present invention is to facilitate uniform andefiicient drying of the filamentary tow.

According to the present invention, a method of spreading a compact towof substantially parallel continuous filaments into a flat band ofsubstantially uniform thickness comprises passing the tow over and inclose proximity to a fiat or substantially flat surface and directing aseries of oblique air jets on to the moving tow, the jets collectivelyhaving'components of velocity both in and transversely to the directionof movement of the tow, so that the air passing through the tow spreadsthe filaments and is immediately defiected back through the tow by thefiat surface. The surface may be entirely fiat or may be provided withspaced transverse ribs which assist in deflecting the air.

In a preferred form of the invention the tow is passe'd through a tubehaving a fiat internal surface on to which jets of air are obliquelydirected in the direction of movement of the tow,

from above the flat surface. The number of air jet is preferablyincreased in the direction of travel of the tow. Reciprocating air jetsmay also be used.

Theprocess of the present invention is useful for spreading a wet towpreparatory to drying on heated rollers but it can be applied to otherprocesses in which it is required to spread a com- 3 Claims. (Cl.19-.48)

- 2 pact tow into a fiat band having a substantially uniform thicknessfor processing purposes.

The present invention is illustrated by way of example in theaccompanying diagrammatic drawings in which Figure l is a plan view of asuitable apparatus for spreading tow by the process according to theinvention, and. V

Figur 2 is a side elevation of the apparatus shown in Figure 1.

Referring to the drawings, a tow I of wet rayon filaments, which haspassed through a series of liquid treatments and then through the nip ofa pair of rollers (not shown) to remove excess liquid, is passed into aflat tube 2 having a narrow converging entrance channel 3 and a.diverging and appreciably longer chamiel 4 where the spreading of thetow takes place. The upper and lower inner surfaces 5, 6 of the tube aresubstantially flat and a total of fifteen pipes I, carrying compressedair supplied from a pipe 8 and a distribution chamber 9 mounted abovethe tube 2 at its narrow end, pass obliquely downwards to open into thetube 2 on its upper, inner surface 5. The pipes 'l are mounted in threegroups containing three, five, and seven pipes respectively, the groupcontaining the three pipes la being arranged near the entrance end, thegroup containing the seven pipes 'lc being arranged near the exit endand the group of five pipes lb being between the other two groups. Eachgroup of pipes is also splayed between the chamber 9 andthe tube 2 sothat the centre pipe of each group is in line with the longitudinal axisof the tube 2 whilst the other pipes form an increasing angle with thelongitudinal axis (in plan view) as they are positioned away from thecentre of each group.

Air jets entering the tube 2 by means of the first group of three pipesla strike the moving tow l causing the filaments to spread out slightly,the immediate deflection of the air jets by the fiat, lower, innersurface 6 of the tube assisting in spreading of the filaments. Thepartially spread tow then passes'under the air jets from the secondgroup of five pipes lb where further spreading takes place and finally,after passing under the jets of air from the third group of seven pipes1c, the tow is spread into a flat band of filaments l0 having asubstantially uniform thickness. The

flat band of filaments I0 is finally dried.

Where there is a tendency for the fiat band of filaments to reform intoa compact tow after passing through a part of the dryer the tow may bepassed through a further spreading tube as .1 described above, beforepassing on to the second part of the dryer.

What I claim is:

1. Apparatus for spreading a compact wet tow of substantiallyparallelcontinuou filaments into a flat band of substantially uniform thicknesscomprising a substantially flat tube having a narrow converging entrancechannel and a divergent exit channel substantially longer than theentrance channel and substantially wider :at -the exit end than thewidth of the entrance channel, for receiving a tow of wet filaments,said tube having substantially flat upp r and lower inner surfaces, anda compressed air supply source above said fiat tube, in combination witha series of group-s of pipes connecting zthexcompressed air source tosaid fiat tube, the groups being-spaced from each other lengthwise ofthe exit channel, and the pipes in each group being spaced from eachother widthwise of said channel, and each of said groups of pipesmeetingthe fiat tube at an acute angle whereby compressed air .from thecompressed air source passes downwardly through said groups of pipes'ina direction which isbo'th transverse to and in line with the movement ofthe tow through said flat tube, and whereby the air from the pipespasses through the tow and strikes the lower fiat surface of saidfiattube and is immediately deflected back through the tow by said lowersurface, thereby spreading the filaments of the tow.

2. Apparatus as claimed in claim 1,. wherein the number of pipes in eachgroup increases in the direction of travel of the tow.

3. Apparatus for spreading a compact wet tow of substantially parallelcontinuous filaments into a flat band of substantially uniform thicknessverging exit channel substantially longer than the entrance channel andsubstantially wider at the exit end than the width of the entrancechannel, for receiving a tow of wet filaments, said .tube havingsubstantially :flat upper and lower :inner surfaces, and a compressedair: supply source above said flat tube, in combination with a series.of three groups of pipes connecting the compressed air source to saidflat tube one group having its-exit near the entrance end of the fiattube; another group having its exit near the exit .end of the vfiat tubeand the third group having .its exit between that of the other two, thecenter pipe-of each group .being in line with the longitudinal axis ofsaid flat tube and the other pipes of each group forming an increasingangle with said'longitudinal-axis as they are positioned away from thecenter of each group, and each of said groups of pipes meeting the fiattube at an acute angle whereby compressed air from the compressed ,airsource :passes downwardly through said groups-of pipes in a directionwhich is both transverse to and .in line with the movement of the twothrough said fiat tube, and whereby the air from the pipes passesthrough the tow and strikes the lower fiat surface of said fiat tube andis immediately deflected back through the tow by said lower surface,thereby spreading the filaments or the tow.

H. B. MERRIMAN.

Re'fierences Cited in the file of this patent UNITED STATES PATENTSNumber Name Date 2,219,356 Dreyfus et a1 Oct. 29, 1940 2,351,549Schwartz June 13, 1944 2,379,824 Mummery July 3, 1945

